Apparatus for surface coating of strip metal or the like



y 8, 1965 c. c. BLACKMAN 3,183,888

APPARATUS FOR SURFACE COATING OF STRIP METAL OR THE LIKE Filed Nov. 29, 1961 3 Sheets-Sheet l I I I I r I I 1 I I 1 N V EN TOR. 644 w/v C BZACKMAN BY 5 Sheets-Sheet 2 C. C- BLACKMAN APPARATUS FOR SURFACE COATING 0F STRIP METAL OR THE LIKE May 18, 1965 Filed Nov. 29, 1961 x; Fig.5

y 1965' c. c. BLACKMAN 3,183,888

APPARATUS FOR SURFACE COATING OF STRIP METAL OR THE LIKE Filed Nov. 29, 1961 s Sheets-Sheet s as 56 a 78 INVENTOR.

Camv CBLAC'AMIM By M I W M \-M Amen/5y:

United States Patent 3,1$3,888 APPARATUS FOR SURFACE COATING 0E STRIP METAL OR THE LIKE Calvin C. Blackmail, Bay Village, Ohio, assignor to Lee Wilson Engineering Company, Inc., Cleveland, Ohio,

a corporation of Ohio Filed Nov. 29, 1961, Ser. No. 155,585 6 Claims. (Cl. 118-495) This invention relates to applying metallic surface coatings to metal parts and more particularly to improved apparatus for coating elongated lengths of strip metal, such as strip steel, with chromium or other metals by a gaseous diffusion process.

A process of applying chromium or other metallic alloying metals to the surface of metallic wire, strip or the like has been proposed by which a case or surface layer of chromium or other metal may be alloyed into the surface of the metal being treated by contact with a suitable coating or alloying agent in a gaseous state under proper temperature and time conditions.

It is the object of the present invention to provide apparatus wherein chromizing (or other metallic coating) of coils of strip steel or other metal may be uniformly, effectively and economically carried out. In this specification, although particular reference will be made to the application of a chromium surface, commonly called chromizing, it is to be understood that where this term is used herein it is intended to extend to and include other procedures such as coating with aluminum, silicon, or other metals.

The above and other objects of my invention will appear from the following description of several embodiments thereof, reference being had to the accompanying drawings, in which:

FIGURE 1 is a vertical cross-sectional view of one form of my apparatus for subjecting open coils of strip metal to chromizing treatment or the like;

FIGURE 2 is a horizontal cross-sectional view, taken substantially on line 22 of FIGURE 1, and illustrating the form and arrangement of the trays for carrying the granular metallic coating material, the wire screening being omitted more clearly to show the perforate bottom wall of the top tray;

FIGURE 3 is an enlarged vertical cross-sectional view, taken substantially on line 33 of FIGURE 2, of several of the upper coating material carrying trays shown in FIGURES 1 and 2;

FIGURE 4 is a view generally similar to FIGURE 1 but illustrating a modified form of chromizing apparatus for treating open coils of strip steel or the like;

FIGURE 5 is a horizontal cross-sectional View taken substantially one line 55 of FIGURE 4 and illustrating the metallic coating material carrying means;

FIGURE 6 is an enlarged fragmentary vertical crosssectional view taken substantially on line 6-6 of FIGURE 5 illustrating the construction of the tubular perforate coating material carrying cylinders seen in FIGURES 4 and 5;

FIGURE 7 is a view generally similar to FIGURES 1 and 4 but illustrating a further embodiment of my apparatus for subjecting open coils of strip metal to chromizing by gaseous diffusion; and

FIGURE 8 is a horizontal cross-sectional view taken substantially on line 8-8 of FIGURE 7.

Referring now to FIGURES 1, 2 and 3, the chromizing apparatus illustrated includes a base structure 1 on which is supported a charge support and a diffuser D having a bottom wall 2, a top wall 3, and a plurality of radially extending diffusing vanes 4. A centrifugal type fan or blower 5 is supported in the central portion of diffuser D on a shaft 6 and is adapted to be driven from a suitable "ice power source (not shown) through a drive pulley 7 or the like. The upper wall 3 of diffuser D is provided with a central opening 8 forming the inlet to the blower 5 and the outer periphery of diffuser D is open at 9 forming an annular outlet passage for the atmosphere moved outwardly by the blower 5.

Supported on the upper wall portion 3 of the diffuser D is a plenum chamber structure P having an outer wall 10, an inclined annular baffle wall 11 and a plurality of radially extending support webs 12. Carried on these radial support webs 12 is a perforate coil supporting grid 13, an outer imperforate ring member 14 and an imperforate center closure plate 15.

When it is desired to chromize a coil of strip steel in my apparatus the coil is first rewound into open form with the laps of the coil spaced apart preferably a distance equal to from one to ten times the thickness of the strip being treated. This may conveniently be effected by the procedure described in the copending application of Lee Wilson and Edwin A. Corns, Serial No. 639,939, filed February 13, 1957, now US. Patent 3,114,539. Such an open coil is indicated at C in FIGURE 1 and is carried by the grid 13 of the plenum chamber P after being placed thereon by an electromagnet or other suitable lifting means. As seen in FIGURE 1, the coil C is disposed with its axis vertical and with the outer lap just overlying the imperforate outer ring 14 of the plenum chamber P and with its inner lap just overlying the outer edge of the center closure plate 15.

In the chromizing process for which my apparatus is adapted to be used a suitable metallic coating material, such as metallic chromium or ferrochrome in finely divided granular form, is caused to be intimately contacted by a stream of atmosphere so that the chromium can be transferred to the steel by contact with this gas in the presence of a suitable activating agent in the form of a gaseous halogen such as hydrogen bromine (HBr). To support the granular metallic coating material in sufilcient quantity to eifect the desired processing of an open coil of strip steel and to permit the fiow of atmosphere therethrough atthe desired rate to accomplish the chromizing operation, I provide a series of superimposed annular coating material carrying trays T. These are arranged in vertically spaced apart stacked or tiered relation and, as best seen in FIGURE 3, are supported and held in position by inclined annular baffle walls or spacers 16 and vertically extending circumferentially spaced apart spacer rods 16.

Each tray T has an annular inner wall 17 and outer wall 18, is open at the top, and has a perforate bottom wall 19 which may conveniently be made of expanded metal or the like having sutficient strength and rigidity to serve its structural function while permitting the free flow of atmos phere therethrough. On top of the perforate bottom wall 19 is a layer of wire screening of sufficiently fine mesh to prevent the passage of the granular metallic coating material, indicated at G in the drawings, therethrough. In some cases it may be desirable to place another annular ring or layer of screening (not shown) on top of the metallic coating material on the trays T to prevent it being picked up by the atmosphere moving through the trays and carried into the coil C.

As seen in FIGURE 1, the stack of trays T is supported on the upper wall portion 3 of the charge support and diffuser D just outside the the plenum chamber P and extends up in spaced relation to the outer periphery of the coil C. To facilitate handling it is preferable that the top tray T of the assembly be disposed slightly below the top of the coil C so that these trays will not have to be removed each time a new coil C is positioned for processing After the open coil C is placed on the grid 13 of plenum chamber P within the bank of trays T as seen in FIGURE 1, a removable housing in the form of an inner cover 21 having an open bottom bell shape is placed over the trays T and coil C. This housing or inner cover 21 is supported at its lower edge on the base 1 and has an outwardly extending portion 22 having dependent flanges 23 and 24 which fit into a sealing channel 25 in the base structure 1. This channel 25 contains oil, sand or other suitable sealing material to form a gas-tight seal between the base 1 and the inner cover 21.

To provide the necessary heat to accomplish the chromizing action a bell-type furnace structure F is removably supported on the base structure 1 and carries a series of circumferentially arranged heating elements such as the radiant combustion tubes 26 of well known type. The heat from the combustion tubes 26 is transferred through and by the wall of the inner cover 21 to the atmosphere circulating within the inner cover. It will be understood that although combustion tubes are illustrated as a source of heat electrical heating elements or other suitable source of heat may be employed. It will also be understood that the base 1, diffuser D, plenum chamber P, trays T, inner cover 21 and furnace F are preferably circular in horizontal crosssectional form and that the furnace structure F is placed over the inner cover 21 preparatory to a chromizing operation and is removed after the heating operation is completed.

In order to direct the flow of atmosphere within the inner cover 21 in the desired path and to cause substantially all of the circulating atmosphere to pass repeatedly through the spaces between the laps of the coil without by-passing or channeling around the outside or through the inside of the coil, I provide a removable top bafile member 27 which has a downwardly depending outer flange portion 27' adapted to rest in an annular sealing trough or channel 28 disposed at the outer periphery of the uppermost tray T. Suitable granular sealing material may be carried in the trough 2.8 to form a substantially gas-tight seal between the top tray T and the baflie member 27. This bailie member 27 is removably supported in the channel 28 and it will be understood that it is placed in position after the coil C is positioned on the top of the plenum chamber P and before the inner cover 21 is dropped over the assembly. Other means may be provided for preventing the by-passing of atmosphere from the blower 5 past the trays T, without going through them, into the coil C. For example, a bafiie wall member could be carried by the inner cover 21 and extend across between the Wall of the cover and the outer periphery of the top tray T.

As it is necessary to purge the atmosphere within the inner cover 21 of air at the start of a chromizing operation, an atmosphere outlet pipe 29 extends up through the base 1 up into the space within the inner cover 21 and is provided with suitable valves and pressure regulating devices (not shown) to control the flow therethrough. One or more gas inlet pipes 30 also extend through the base 1 and, as seen in FIGURE 1, preferably have their upper outlet ends 30' disposed closely adjacent the coating material carrying trays T.

In the operation of the apparatus described above, assuming that the trays T are properly filled with a suitable metallic coating material, for example finely divided metallic chromium or ferrochrome if chromizing is to be carried out, the open coil C is placed in position on the grid 13 of the plenum chamber P, the top baffle member 27 is put in place and the inner cover 21 is then lowered over the entire assembly. Next the belltype heating furnace F is positioned over the inner cover 21 and the atmosphere within the bell 21 is purged of air by Causing a suitable carrier gas, for example a mixture of approximately 95% nitrogen and 5% hydrogen, to be charged into the bell 21 through the pipes 30 while permitting the escape of atmosphere through the outlet 29.

During or after the purging operation the furnace F is fired up to proper temperature and the blower 5 is started. Because of the arrangement of the baffles and support members the flow of the atmosphere circulated by the blower 5 is, as seen from the arrows of FIG- URE 1, radially outwardly from the blower 5 past the diffuser vanes 4, out through the outlet passage 9 and upwardly along the wall of the inner cover 21 where it is heated by heat from the combustion tubes 26. Due to the inclined baffie spacers 16 between the trays T, and to the top bat-fie member 27, all of the atmosphere must necessarily pass upwardly in parallel flow, as distinguished from series or sequential flow, through the open grids 19 of the several trays T and through the granular material G thereon. It then passes up along the outer surface of the open coil C and, as it cannot pass down through the center opening in coil C because of the closure plate 15, moves downwardly through the spaces between the laps of the coil C in intimate contact with all parts of the entire surface of the strip material making up the coil. After the atmosphere leaves the bottom of open coil C it passes through the supporting grid 13 and is directed by the inclined bat-He wall 11 to the inlet opening 8 of the blower 5. This circulation is continued as long as the blower 5 operates.

In the chromizing operation, in order to elfect alloying of chromium on the surface of the steel, it is necessary to employ a suitable catalyst or activating agent, for example hydrogen bromine. However, it is normally desirable, in chromizing of steel, to change the furnace atmosphere to substantially pure hydrogen and to bring the work (the open coil) up to a temperature of, for example, 1600 F. before the activating agent is added to the circulating atmosphere. With the apparatus described circulation of the initial purging gas nitrogen and 5% hydrogen) within the inner cover 21 may be continued for a period long enough to bring the metal of the coil C up to about 1100 F. and then this gas replaced through pipes 30 by an atmosphere of substantially pure hydrogen. Heating is continued, still with no chromizing action, and when the proper temperature (1600 F. in the present example) is attained, the activating agent is injected through the pipe or pipes 3%, or other suitable inlet opening preferably in close proximity to the metallic coating material in the trays T, and circulation is continued until the desired case or coating is formed on the strip. While the activating gas is entering the space within the inner cover 21 a corresponding quantity of atmosphere will be permitted to escape through the outlet 29. If desired this exiting gas may be treated for recovery of usable materials contained therein or cleaned and separated into its constituents for reuse. After chromizing is completed and the coil has cooled down to about 1200 F. the hydrogen atmosphere may be replaced, using inlet and outlet pipes 30 and 29, with the 95% nitrogen and 5% hydrogen atmosphere for final cooling.

By providing a plurality of trays T, arranged for parallel flow of the circulating atmosphere therethrough, a large volume of powdered or granular coating material G may be utilized so that each time the atmosphere recirculates through the trays T it will pick up additional chromium and there will be an adequate supply to produce the desired coating, not only on one coil but on a succession of coils, before the material becomes depleted and it is necessary to empty the trays T and recharge them with a new supply of coating material.

By use of the apparatus described the circulating atmosphere may be utilized first to heat the charge to the desired temperature without coating action and then, after admission of the activating agent, for conveying the metallic chromium from the granular material G to, and distributing it uniformly and evenly over, the entire surface of the strip metal making up the open coil C.

In FIGURES 4-6 a modified form of my chromizing 3,1 eases apparatus is illustrated in which the flow of atmosphere is upwardly through the open coil, rather than downwardly as in the apparatus of FIGURE 1, and the metallic coating material is carried by containers disposed within the center opening in the coil, thus permitting open coils of larger outside diameter to be handled in a furnace of a given diameter. Referring to FIGURE 4, the furnace F and the inner cover 21 are substantially like those shown in FIGURE 1 and are removably supported on a base structure 1 which supports a blower 5 in the same general arrangement as FIGURE 1. Accordingly, corresponding parts have been identified by the same reference characters. A combination diffuser for the blower -5 and coil support for the open coil C is generally indicated at 35. This is supported on the base 1 and includes an outer wall 36, a plurality of radial diffuser and coil support vanes 37 and a coil supporting perforate grid 38. Inclined circumferentially extending deflector blades 39 may be positioned between the radial vanes 37 to direct the output of the blower 5 upwardly through the grid 38 into the bottom of the open coil C.

To prevent by-passing of the atmosphere around the coil C an imperforate outer ring portion 39 is provided 7 at the outer periphery of grid 35 and an inner imperforate ring portion 40 defines the inner circumference of grid 38. An inclined baffle member 41 having a center opening 42 extends inwardly from ring 40 and defines the inlet for the blower 5. Another inclined imperforate baffle member 43 projects inwardly and upwardly from ring 40 and carries the supporting plate 44 for the tubular perforate sleeves or containers S and S which carry the granular metallic coating material in this embodiment of my invention.

As best seen in FIGURE 6, the inner tubular container S comprises spaced inner and outer walls 45 and 46 of expanded metal or other perforate'material. To retain the granular coating material 47 in the container, a wire screen sleeve 48 is disposed just inside the outer expanded metal wall 46 and a similar wire screen sleeve 49 is disposed just outside of the inner expanded metal wall 45. Suitable spacers to maintain the proper distance between the inner wall 45 and outer wall 46 of container S are provided and the outer container S is of the same construction. stiffening ribs 50 (see FIGURE 5) extend between the outer and inner containers S and S and a top cover plate 51 extends across the tubular containers S and S. In order properly to channel the flow of atmosphere so that it will move radially inwardly through the outer container S and radially outwardly through the inner container S in parallel flow and then into the annular passageway 52 formed therebetween, the top cover plate 51 is imperforate except for a central opening 51' which permits atmosphere to enter the center of the inner tubular container S. The bottom supporting plate 44 is imperforate except for an annular opening 44' disposed below and coextensive with the annular passageway between the outer and inner containers S and S.

An atmosphere inlet pipe 53 and an atmosphere outlet pipe 54 extend up through base 1 into the coil support and diffuser 35. In addition another pipe 55 may be provided for directing a gaseous activating agent into the circulating atmosphere at the proper time as has been previously explained.

When the apparatus of FIGURES 4-6 is employed for chromizing open coils of strip metal the tubular containers S and S are filled with granular metallic coating material and are positioned as indicated with the cover plates 44 and 51 in place. An open coil C is then lowered over the containers S and S until it is supported on the grid 38. Next the inner cover 21 is placed over the charge and then the furnace F is positioned. When the blower 5 is driven the atmosphere will be moved outwardly through the diffuser vanes 37 and, as it has no other possible path, will flow upwardly through the spaces between the laps of the open coil C. As shown by the arrows in FIGURE 4 the atmosphere leaving the top of the open coil C can only get back to the blower 5 by passing either radially inwardly through the outer tubular container S and through the granular material therein, or by passing radially outwardly through the inner container S and the granular material contained therein. As the containers S and S are arranged for parallel flow of atmosphere therethrough and are packed full of the material 47 right up to the top plate 51 the entire volume of the atmosphere must pass through the granular coating material 47 between each successive passage through the open coil C. It then flows downwardly through the annular space 52 and, because of the bafiie walls 41 and 43, it is returned directly to the blower 5 for recirculation.

When it is necessary to replace the granular material 47 the entire assembly of outer and inner containers S and S may be lifted off the base 1, the cover plate 51 removed, the depleted material emptied out and replaced with new material. As all of the metallic coating material is contained within the opening in the center of the open coil in the embodiment of FIGURE 4, the outer diameter of the open coil being treated may be larger, for a given diameter inner cover 21 and furnace F, than would be the case for the apparatus of FIGURE 1. In like manner the same outer diameter open coil could be handled in a smaller diameter furnace with the arrangement of FIGURE 4 than with that of FIG- URE 1.

In FIGURES 7 and 8 I have illustrated a third embodiment of my apparatus wherein the base 1, inner cover 21 and blower 5 are substantially the same as those previously shown and described. In this embodiment the diffuser 60 includes the usual radial vanes 61, is supported on the base 1, and has an imperforate top wall 62. An annular atmosphere outlet 63 is formed at the outer periphery of the diffuser 60 and a coil support and plenum chamber P is supported on the top 62 of the diffuser 60. This plenum chamber P is substantially the same in form as the plenum chamber structure P .of FIGURE 1 and, therefore, will not be further described and its parts are indicated by similar reference numerals.

As seen in FIGURE 7, the diameter of the outer wall 36 and plenum chamber P is smaller than the outer diameter of top wall 62 of the diffuser 60. This provides an annular ledge or flange indicated at 62 on which an imperforate tubular sleeve 64 is supported. This tubular sleeve 64 is preferably made of corrugated sheet metal, with the corrugations extending vertically, in order to provide the desired rigidity and stiflness and an open grid support structure 65 extends across the top of sleeve 64.

The open grid 65 serves as a support for a plurality of concentric annular material containing sleeves indicated at 66, 67, 68, 69, 76 and 71. These sleeves are preferably constructed in the same manner as the sleeves S and S' seen in FIGURES 4, 5 and 6 and are filled with granular coating material indicated at 72. Top and bottom flow directing plates, 73 and 74 respectively, are disposed at the ends of the sleeves 66-71. The top plate 73 is imperforate in the area above and between sleeves 66 and 67, provided with an annular opening between sleeves 67 and 68, imperforate above and between sleeves 68 and 69, open between sleeves 69 and 70, imperforate above and between sleeves 70 and 71, and provided with a central opening 75.

The bottom flow directing plate 74 is imperforate below sleeve 66, open between sleeves 66 and 67, imperforate below and between sleeves 67 and 68, open between sleeves '68 and 69, imperforate below and between sleeves 69 and 70, open between sleeves 70 and 71, and imperforate across the center opening in sleeve 71. These top and bottom flow directing plates 73 and 74 cause the entire volume of circulating atmosphere to pass in parallel flow through the several coating material sleeves 66-71.

As is clearly seen by the arrows in FIGURE 7, the atmosphere from the blower moves outwardly through the diffuser 60 and the outlet opening 63 and then upwardly through the annular space between the side wall of the inner cover 21 and the imperforate supporting sleeve or cylinder 64. Because of the upper flow directing plate 73 the atmosphere may pass only radially inwardly through sleeve 66, outwardly through sleeve 67, inwardly through sleeve 68, outwardly through sleeve 69, inwardly through sleeve 7 0, and outwardly through sleeve 71 in parallel flow. As the annular space 76 between sleeves 66 and 67, space 77 between sleeves 63 and 69, and space 78 between sleeves 70 and '71 are each open at the bottom, the atmosphere will move downwardly therethrough and then down through the space between the laps of the open coil C into the plenum chamber P where it is directed by the baflie wall 11 back to the inlet of the fan 5. All of the atmosphere must pass through the coil C" because it is blocked off by the sleeve 64, the imperforate outer ring 14 and, at the inside of the coil, by the center closure plate 15.

With the apparatus of FIGURES 7 and 8 a very large volume of granular metallic coating material may be supported within the inner cover 21 while maintaining the diameter of the inner cover only slightly larger than the outside diameter of the open coil being treated. The entire assembly of corrugated cylinder 64, top grid structure 65, and the material containing sleeves 66-71 with their cover plates may be made integral for removal from the base 1 as a unit. With this apparatus the coil C" is first positioned on the plenum chamber P, the assembly just referred to is lowered into place over the coil, and the inner cover then located on the base. It will be understood that a furnace similar to furnace F of FIG- URES l and 4 will be employed to supply the heat necessary for the chromizing process.

Although I have illustrated and described herein several embodiments of my invention it will be understood that other structural arrangements and designs might be employed without departing from the spirit of my invention. I do not, therefore, Wish to be limited to the particular apparatus herein specifically disclosed but claim as my invention all embodiments thereof coming within the scope of the appended claims.

I claim:

1. Apparatus for applying a metallic coating to strip metal in open coils having spaced apart laps including, a base structure, a charge support on said base structure having a perforate coil supporting area on which an open coil may be placed with its axis vertical, a plurality of metallic coating material carrying containers supported by said base structure, blower means, a removable housing adapted to be supported on said base structure and to enclose said charge support and an open coil supported thereon and said coating material carrying containers, means for directing substantially the entire volume of atmosphere moved by said blower means through the spaces between the laps of said open coil and then in parallel flow through bodies of metallic coating material carried by said coating material carrying containers whereby the entire volume of atmosphere within said housing will be continuously and repeatedly circulated through the spaces between the laps of said open coil and, between each passage through said open coil, in parallel flow through bodies of coating material on said coating material carrying means, containers for driving said blower means, means for directing a gaseous activating agent into the space within said housing, and means for heating the circulating atmosphere.

2. Apparatus for applying a metallic coating to strip metal in open coils having spaced apart laps comprising a base structure, a charge support on said base structure having a perforate coil supporting area on which an open coil may be placed with its axis vertical, metallic coating material carrying means supported adjacent a coil on said supporting area, blower means on said base structure, means for directing the entire volume of atmosphere moved by said blower means to said metallic coating material carrying means, means for directing the entire volume of said atmosphere through metallic coating material carried by said carrying means, means for directing the entire volume of said atmosphere, after it has passed through said coating material carrying means, into the spaces between the laps of an open coil on said coil supporting area, means for directing the entire volume of said atmosphere as it leaves said open coil back to said blower means, a removable housing adapted to be supported on said base structure and enclosing said charge support and metallic coating material carrying means, and drive means for said blower means whereby said blower may be operated to continuously and repeatedly circulate the atmosphere within said housing through metallic coating materials on said supporting means and an open coil on said charge support, means for directing a gaseous activating agent into the space within said housing, and means for heating said circulating atmosphere.

3. In apparatus for applying a metallic coating to open coils of strip metal including a base structure for supporting an open coil with its axis vertical, a removable housing supported on said base structure for enclosing an open coil supported on said base structure, blower means for circulating the atmosphere with said removable housing, and bafiie means for directing the entire volume of said circulating atmosphere repeatedly through said open coil, the provision of a plurality of spaced apart perforate coating material carrying containers supported by said base structure within said removable housing in the path of said circulating atmosphere and adapted to be spaced from an open coil supported on said base structure, bafiie means for directing the flow of said circulating atmosphere through said coating material carrying containers in parallel flow, bafiie means for blocking the passage of said circulating atmosphere between said blower means and one end of an open coil supported on said base structure without first passing through said coating material carrying containers whereby the entire volume of said circulating atmosphere will pass through said coating material carrying containers in parallel flow between each successive passage thereof through an open coil supported on said base structure, means for directing a gaseous activating agent into the space Within said housing, and means for heating said circulating atmosphere.

4. In apparatus for applying a metallic coating to open coils of strip metal including a base structure for supporting an open coil with its axis vertical, a removable housing supported on said base structure for enclosing an open coil supported on said base structure, blower means for circulating the atmosphere within said removable housing, and baffle means for directing the entire volume of said circulating atmosphere repeatedly downwardly through said open coil, the provision of a plurality of superimposed vertically spaced apart annular perforate bottom coating material carrying trays supported by said base structure within said removable housing and having their inner peripheries disposed to be radially outwardly spaced from the outer periphery of an open coil supported on said base structure, a plurality of inclined annular battle Walls one extending from one periphery of each of said trays to the opposite periphery of the adjacent tray, said inclined baflie walls being disposed to direct the flow of said circulating atmosphere through said coating material carrying trays in parallel flow, battle means for blocking the passage of said circulating atmosphere between said blower means and the upper end of an open coil supported on said base structure without first passing through said coating material carrying trays whereby the entire volume of said circulating atmosphere will pass in parallel flow through said coating material carrying trays between each successive passage thereof through an open coil supported on said base structure, means for directing a gaseous activating agent into the space within said housing, and means for heating said circulating atmosphere.

5. In apparatus for applying a metallic coating to open coils of strip metal including a base structure for supporting an open coil with its axis vertical, a removable housing supported on said base structure for enclosing an open coil supported on said base structure, and blower means for circulating the atmosphere within said removable housing, the provision of halide means for directing the entire volume of said circulating atmosphere repeatedly upwardly through said open coil, a plurality of concentric radially spaced apart tubular coating material carrying containers supported by said base structure and disposed to be within the center opening of an open coil supported on said base structure, each of said containers having perforate spaced apart inner and outer walls, the outer periphery of the outermost of said containers being adapted to be radially inwardly spaced from the periphery of the center opening of an open coil supported on said 'base structure, end cover plate means for said tubular coating material containers disposed to direct the entire volume of said circulating atmosphere as it leaves the upper end of an open coil supported on said base structure to flow radially through said concentric tubular coating material containers in parallel flow, bafile means for blocking the passage of circulating atmosphere from the upper end of an open coil supported on said base structure to said blower means without first passing through said coating material carrying containers whereby the entire volume of said circulating atmosphere will pass in parallel flow through said coating material carrying containers between each successive passage thereof through an open coil supported on said base structure, means 'for directing a gaseous activating agent into the space within said housing, and means for heating said circulating atmosphere.

6. In apparatus for applying a metallic coating to open coils of strip metal including a base structure for supporting an opencoil with its axis vertical, a removable housing supported on said base structure for enclosing an open coil supported on said base structure, blower means for circulating the atmosphere within said removable housing, and bafile means for directing the entire volume of said circulating atmosphere repeatedly through said open coil, the provision of a plurality of concentric annular radially spaced apart material containing sleeves supported by said base structure and adapted to be disposed above the upper end of an open coil supported on said base structure, each of said sleeves-having perforate spaced apart inner and outer walls, top and bottom flow directing plates at the top and bottom ends respectively of said material containing sleeves, said plates being disposed to direct the entire volume of said circulating atmosphere radially through said material containing sleeves in parallel flow, an imperforate tubular sleeve removably supported on said base structure and adapted to enclose an open coil supported on said base structure, said bottom flow directing plate being supported on the upper end of said imperforate tubular sleeve and said tubular sleeve being positioned to block the passage of said circulating atmosphere between said blower means and the upper end of an open coil supported on said base structure without first passing through said concentric annular material containing sleeves whereby the entire volume of said circulating atmosphere will pass in parallel flow through said material containing sleeves between each successive passage thereof through an open coil supported on said base structure, means for directing a gaseous activating agent into the space within said housing, and means for heating said circulating atmosphere.

References Cited by the Examiner UNITED STATES PATENTS 2,543,710 2/51 Schmidt et a1. 148-635 2,801,187 7/57 Gallniche l17l07.2 X 2,836,513 5/58 Samuel 117107.2 X

OTHER REFERENCES Arnold: Open Coil-Process, in Iron and Steel Engineer 37(8): pages 91-111, August 1960, T8300, I65.

RICHARD D. NEVIUS, Primary Examiner. 

1. APPARATUS FOR APPLYING A METALLIC COATING TO STRIP METAL IN OPEN COILS HAVING SPACED APART LAPS INCLUDING A BASE STRUCTURE, A CHARGE SUPPORT ON SAID BASE STRUCTURE HAVING A PERFORATE COIL SUPPORTING AREA ON WHICH AN OPEN COIL MAY BE PLACED WITH ITS AXIS VERTICAL, A PLURALITY OF METALLIC COATING MATERIAL CARRYING CONTAINERS SUPPORTED BY SAID BASE STRUCTURE, BLOWER MEANS, A REMOVABLE HOUSING ADAPTED TO BE SUPPORTED ON SAID BASE STRUCTURE AND TO ENCLOSE SAID CHARGE SUPPORT AND AN OPEN COIL SUPPORTED THEREON AND SAID COATING MATERIAL CARRYING CONTAINERS, MEANS FOR DIRECTING SUBSTANTIALLY THE ENTIRE VOLUME OF ATMOSPHERE MOVED BY SAID BLOWER MEANS THROUGH THE SPACES BETWEEN THE LAPS OF SAID OPEN COIL AND THEN IN PARALLEL FLOW THROUGH BODIES OF METALLIC COATING MATERIAL CARRIED BY SAID COATING MATERIAL CARRYING CONTAINERS WHEREBY THE ENTIRE VOLUME OF ATMOSPHERE WITHIN SAID HOUSING WILL BE CONTINUOUSLY AND REPEATEDLY CIRCULATED THROUGH THE SPACES BETWEEN THE LAPS OF SAID OPEN COIL AND, BETWEEN EACH PASSAGE THROUGH SAID OPEN COIL, IN PARALLEL FLOW THROUGH BODIES OF COATING MATERIAL ON SAID COATING MATERIAL CARRYING MEANS, CONTAINERS FOR DRIVING SAID BLOWER MEANS, MEANS FOR DIRECTING A GASEOUS ACTIVATING AGENT INTO THE SPACE WITH SAID HOUSING, AND MEANS FOR HEATING THE CIRCULATING ATMOSPHERE. 